One of the most frightening aspects of cancer is its ability to spread, or metastasize. Initially, cancer cells are found grouped together thereby forming one or more tumors. After formation of the primary tumor, cancer cells can gain the ability to separate from the original tumor and travel to other areas of the body. Lung cancer cells that take up in the liver and form tumors are still lung cancer cells. Thus, the propensity for one particular form of cancer to metastasize is dependent on many factors, including type of cancer; however, the overall process of how cells begin the process of metastasis is still not completely under stood.
If a single localized tumor is discovered before it has had a chance to metastasize, then the prognosis of patient survival is higher. This is because the tumor can be effectively excised or destroyed by radiation or chemotherapy. There is, therefore, a difference between tumor growth and metastasis of the tumor cells; the first does not always lead to the other. Cancers that have metastasized, however, are difficult to cure because the extent to which they have spread throughout the body is sometimes not discernable.
In order to metastasize, a cancer cell must break away from its tumor and invade either the circulatory or lymph system. The free cells are then carried to a new location where they establish themselves. Although the body has natural safeguards that prevent cell from surviving after being detached from their natural location, some cancer cells have the ability to over come these safeguards. Therefore, if metastasis is stopped or significantly reduced, the extent of cancer can be determined and subsequently treated. As such, a follow up treatment to cancer therapy wherein a tumor has been excised or radiation/chemotherapy has been used, would be the treatment of the patient to an anti-metastasizing agent. There is a long felt need for methods of preventing cancer cell metastasis.
The growth of primary tumors also presents a challenge to treatment. If the growth of a primary tumor goes unchecked, the initial tumor can grow to a size that adversely effects organ function at the primay site and in nearby tissues. Metastases of the primary tumor are also more likely if the primary tumor's growth is uncontrolled. There is a need for methods of slowing or preventing tumor growth.